Apparatus and method of generating and maintaining orthogonal connection identifications (CIDs) for wireless networks

ABSTRACT

A first device is configured to select and utilize a connection identifier (CID) for a peer-to-peer communication connection between the first device and a second device in a wireless communications network. The CID is selected from a predetermined set of a plurality of CIDs. Prior to selecting the connection identifier, the first device monitors a CID broadcast channel to determine whether the CID is being utilized by other nearby connections. If it is determined that the CID is being utilized by another connection in the proximity, a different (unused) CID is selected. A transmission request is transmitted to the second device using a first transmission resource unit within a traffic management channel slot, the first transmission resource unit being determined as a function of the selected CID. The first device transmits traffic data to the second device in a traffic channel slot corresponding to the traffic management channel slot.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent claims priority to U.S. ProvisionalApplication No. 60/948,882 entitled “Apparatus and Method of Generatingand Maintaining Orthogonal Transmission Identifications (CIDs) forWireless Networks” filed Jul. 10, 2007, and assigned to the assigneehereof and hereby expressly incorporated by reference herein.

BACKGROUND

1. Field

The following description generally relates to wireless communicationsand, in particular, generating and maintaining orthogonal transmissionCIDs in a wireless network where both ad hoc and local access point (AP)communications coexist.

2. Background

Wireless communication systems are widely deployed to provide varioustypes of communication; for instance, voice and/or data may be providedvia such wireless communication systems. A typical wirelesscommunication system, or network, can provide multiple users access toone or more shared resources. For instance, a system may use a varietyof multiple access techniques such as Frequency Division Multiplexing(FDM), Time Division Multiplexing (OFDM), and others.

Common wireless communication systems employ one or more base stationsthat provide a coverage area. A typical base station can transmitmultiple data streams for broadcast, multicast and/or unicast services,wherein a data stream may be a stream of data that can be of independentreception interest to a wireless terminal. A wireless terminal withinthe coverage area of such base station can be employed to receive one,more than one, or all the data streams carried by the composite stream.Likewise, a wireless terminal can transmit data to the base station oranother wireless terminal.

Wireless communication systems leverage various portions of wirelessspectrum for transferring data. However, wireless spectrum is anexpensive and valuable resource. For example, significant costs may beincurred by a company desiring to operate a wireless communicationsystem over a portion of the wireless spectrum (e.g., within thelicensed spectrum). Further, conventional techniques typically provideinefficient utilization of wireless spectrum. According to a commonillustration, the spectrum allocated for wide area network cellularcommunication oftentimes is not uniformly utilized across time andspace; thus a significant subset of spectrum may be unused in a givengeographic location in a given time interval.

According to another example, wireless communication systems often timesemploy peer-to-peer or ad hoc architectures whereby a wireless terminalmay transfer signals directly to another wireless terminal. As such,signals need not traverse through a base station; rather, wirelessterminals within range of each other may discover and/or communicatedirectly. However, conventional peer-to-peer networks typically operatein an asynchronous manner whereby peers may effectuate differing tasksat a particular time. Consequently, peers may encounter difficultyassociated with identifying and/or communicating with disparate peerswithin range, power may be inefficiently utilized, and so forth.

Therefore, a way is needed to allocate and or maintain peer identifierswithin peer-to-peer communication networks that utilize a sharefrequency spectrum.

SUMMARY

The following presents a simplified summary of one or more embodimentsin order to provide a basic understanding of some embodiments. Thissummary is not an extensive overview of all contemplated embodiments,and is intended to neither identify key or critical elements of allembodiments nor delineate the scope of any or all embodiments. Its solepurpose is to present some concepts of one or more embodiments in asimplified form as a prelude to the more detailed description that ispresented later.

In an adhoc peer-to-peer communication network between wireless devices,an orthogonal connection identifier selection scheme is implemented tominimize interference between nearby wireless devices that concurrentlyuse a shared frequency spectrum. In this orthogonal connectionidentifier scheme, a peer-to-peer connection avoids connectionidentifiers being used by other connections in its proximity.

A first device is configured to utilize a first connection identifierfor a peer-to-peer communication connection between the first device anda second device in a wireless communications network. A first connectionidentifier broadcast signal corresponding to the first connectionidentifier is sent by the first device in a connection identifierbroadcast channel. The first device then monitors the connectionidentifier broadcast channel to determine whether the first connectionidentifier is being utilized by another connection in the proximity. ifthe first device determines that the first connection identifier isbeing utilized by another connection in the proximity, it switches to asecond connection identifier for its peer-to-peer connection with thesecond device.

The first and second connection identifiers may belong to apredetermined set of a plurality of connection identifiers. Theconnection identifier broadcast channel may include a plurality ofsymbols in a time interval. The first connection identifier broadcastsignal is sent in one of the symbols. In monitoring the connectionidentifier broadcast channel, the first device may (a) receive a signalin the remaining symbols of the connection identifier broadcast channelin the time interval, (b) detect the presence of a second connectionidentifier broadcast signal in the received signal, the secondconnection identifier broadcast signal corresponding to the firstconnection identifier, and (c) measures the signal strength of thedetected second connection identifier broadcast signal if the presenceof the second connection identifier broadcast signal is detected.

The first device may determine that the first connection identifier isbeing utilized by other connections in the proximity if it is determinedthat either: (a) the second connection identifier broadcast signal ispresent in the received signal, or (b) the signal strength of the secondconnection identifier broadcast signal in the received signal is abovecertain threshold, or (c) the ratio of the signal strength of the secondconnection identifier broadcast signal and the signal strength of aconnection identifier broadcast signal corresponding to anotherconnection identifier in the received signal is above certain threshold.

Prior to sending the first connection identifier broadcast signal, thefirst device may select one of the plurality of symbols of theconnection identifier broadcast channel in the time interval to send thefirst connection identifier broadcast signal. The first device may thenreceive a broadcast signal from a common network timing source. A valueof a time counter may then be determined as a function of the receivedbroadcast signal and changes from one time interval to another. Theselected one of the plurality of symbols may be selected as a functionof the value of the time counter.

Each of the plurality of symbols may be an OFDM symbol including aplurality of tones, and the first connection identifier broadcast signalmay be sent in one of the plurality of tones in the selected one ofplurality of symbols. The combination of selected OFDM symbol and tonemay be determined as a function of the first connection identifier wherea different connection identifier corresponds to a different combinationof selected OFDM symbol and tone. A plurality of OFDM symbols may beassociated with the first connection identifier, where the selected oneof the plurality of symbols is selected from the plurality of OFDMsymbols being associated with the first connection identifier as afunction determined by both the first and the second devices.

The second connection identifier broadcast signal may be received in theremaining OFDM symbols of the plurality of OFDM symbols being associatedwith the first connection identifier. Prior to switching to the secondconnection identifier, the first device may monitor a connectionidentifier broadcast channel corresponding to the second connectionidentifier to determine whether the second connection identifier isbeing utilized by other connections in the proximity. The first devicedetermines to switch to the second connection identifier if it isdetermined that the second connection identifier is not being utilizedby another connection in the proximity.

In determining whether the second connection identifier is beingutilized by other connections in the proximity, the first device may (a)detect the presence of a connection identifier broadcast signal in theconnection identifier broadcast channel, the connection identifierbroadcast signal corresponding to the second connection identifier; and(b) measures the signal strength of the connection identifier broadcastsignal if the presence of the connection identifier broadcast signal isdetected.

The connection identifier broadcast channel may be part of a frequencyspectrum shared with a plurality of other peer-to-peer connections.

The various features describe herein may be implemented within awireless device, a circuit or processor incorporated in a wirelessdevice, and/or a software.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, nature, and advantages may become apparent from thedetailed description set forth below when taken in conjunction with thedrawings in which like reference characters identify correspondinglythroughout.

FIG. 1 is a block diagram illustrating the how an ad hoc peer-to-peernetwork may be implemented in conjunction with a wide area network.

FIG. 2 illustrates one example of a timing sequence for a trafficchannel slot that may be used by wireless terminals to transport trafficafter a peer-to-peer communication connection has been establishedbetween wireless terminals.

FIG. 3 is a block diagram illustrating an environment in which aplurality of wireless terminals may establish peer-to-peer communicationconnections that may cause interference to other nearby wirelessterminals.

FIG. 4 illustrates one example of a channel architecture in which acontrol slot in inserted every so often between traffic slots.

FIG. 5 illustrates an example time-frequency (grid) resource availablefor transmitting and/or receiving signals over a peer-to-peer networkduring a control or traffic channel interval.

FIG. 6 illustrates one example of a timing sequence for a CID broadcastincluding a CID broadcast period and a paging period.

FIG. 7 illustrates one example of a two-part CID broadcast structurewhere each part covers the whole transmission CID space.

FIG. 8 illustrates one example of a four-part CID broadcast structurewhere each part covers the whole transmission CID space.

FIG. 9 (comprising FIGS. 9A and 9B) is a block diagram illustrating theuse of orthogonal transmission CIDs within a peer-to-peer communicationconnection between terminals.

FIG. 10 illustrates a method operational in a first device for avoidingchannel collisions and interference in peer-to-peer networks.

FIG. 11 illustrates a method for determining whether a connectionidentifier is or is not being used by another connection within apeer-to-peer network.

FIG. 12 is a block diagram illustrating another use of orthogonaltransmission CIDs within a peer-to-peer communication connection betweenterminals.

FIG. 13 illustrates a method of operating a first device for maintaininga connection identifier for a peer-to-peer communication connectionbetween the first device and a second device in a wirelesscommunications network.

FIG. 14 is a block diagram illustrating another use of orthogonaltransmission CIDs within a peer-to-peer communication connection betweenterminals.

FIG. 15 illustrates a method operational in a first device for selectingand utilizing a connection identifier for a peer-to-peer communicationconnection between the first device and a second device in a wirelesscommunications network.

FIG. 16 is a diagram illustrating the traffic management channel usingorthogonal CIDs.

FIG. 17 is a block diagram illustrating an example of a wirelessterminal that may be configured to perform orthogonal transmission CIDselection in a peer-to-peer network.

FIG. 18 is a block diagram of another embodiment of a wireless terminalthat may be configured to perform orthogonal transmission CID selectionin a peer-to-peer network.

DETAILED DESCRIPTION

Various embodiments are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more embodiments. It may be evident, however,that such embodiment(s) may be practiced without these specific details.In other instances, well-known structures and devices are shown in blockdiagram form in order to facilitate describing one or more embodiments.

In one embodiment, there is disclosed an apparatus and method ofgenerating a transmission connection identifier (CID) for atransmitter/receiver pair in a wireless network comprising generating anorthogonal transmission CID for the transmitter/receiver pair, andsignaling a transmission intention of the transmitter. This embodimentgenerates transmission connection CIDs which are not likely to collideinto each other in a two-hop neighborhood. When a transmitter wants tostart a conversation with a certain neighboring node, it first grabs adeterministic transmission CID which is not used in its neighborhood.This can be done by using a CID broadcast period, which for example ismade the same as a paging period where the mobiles may ping each otherto start the conversation. Right after the paging period, the currentusers broadcast the transmission CIDs in use in the CID broadcast periodand the new transmitter/receiver pair listen in this period. Thetransmitter/receiver then exchange the CIDs they see in the transmissionCID determination period they see in the CID broadcast period andjointly choose an unused CID.

In another embodiment, a wireless terminal is configured to operate as atransmitter/receiver in a wireless network, comprising means fordetecting an orthogonal transmission CID for the transmitter/receiverpair, and means for signaling a transmission intention of thetransmitter. The wireless terminal may further comprise means forlistening for transmission CIDs during a transmission CID determinationperiod, and means for choosing an unused transmission CID for thetransmitter/receiver pair.

To the accomplishment of the foregoing and related ends, the one or moreembodiments comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe one or more embodiments. These aspects are indicative, however, ofbut a few of the various ways in which the principles of variousembodiments may be employed and the described embodiments are intendedto include all such aspects and their equivalents.

Ad Hoc Communication System

An ad hoc peer-to-peer wireless network may be established among two ormore terminals without intervention of a centralized network controller.In some examples, the wireless network may operate within a frequencyspectrum shared among a plurality of wireless terminals.

FIG. 1 is a block diagram illustrating the how an ad hoc peer-to-peernetwork may be implemented, e.g., in conjunction a wide area network. Insome examples, the peer-to-peer network and the wide area network mayshare the same frequency spectrum. In other examples, the peer-to-peernetwork is operated at a different frequency spectrum, e.g., a spectrumdedicated to the use of the peer-to-peer network. A communication system100 may comprise one or more wireless terminals WT-A 102, WT-B 106, andWT-C 112. Although just three wireless terminals WT-A 102, WT-B 106, andWT-C 112 are depicted, it is to be appreciated that communication system100 may include any number of wireless terminals. The wireless terminalsWT-A 102, WT-B 106, and WT-C 112 can be, for example, cellular phones,smart phones, laptops, handheld communication devices, handheldcomputing devices, satellite radios, global positioning systems, PDAs,and/or any other suitable device for communicating over wirelesscommunication system 100.

According to one example, the communication system 100 may support awide area network (WAN) which may include one or more access nodes AN-A104 and AN-B 110 (e.g., base station, access point, etc.) and/or anynumber of disparate access nodes (not shown) in one or moresectors/cells/regions that receive, transmit, repeat, etc., wirelesscommunication signals to each other and/or to the one or more wirelessterminals WT-A 102, WT-B 106, and WT-C 112. Each access node AN-A 104and AN-B 110 may comprise a transmitter chain and a receiver chain, eachof which can in turn comprise a plurality of components associated withsignal transmission and reception (e.g., processors, modulators,multiplexers, demodulators, demultiplexers, antennas, . . . ) as will beappreciated by one skilled in the art. According to an optional feature,when communicating through the WAN, the wireless terminal(s) maytransmit signals to and/or receive signals from an access node whencommunicating via the wide area infra-structure network supported by thecommunication system 100. For instance, wireless terminals WT-A 102 andWT-B 106 may communicate with the network via access node AN-A 104 whilewireless terminal WT-C 112 may communication with a different accessnode AN-B 110.

The wireless terminals may also communicate directly with each other viaa local area peer-to-peer (P2P) network (e.g., ad hoc network).Peer-to-peer communications may be effectuated by directly transferringsignals between wireless terminals. Thus, the signals need not traversethrough an access node (e.g., a base station) or centrally managednetwork. The peer-to-peer network may provide short range, high datarate communication (e.g., within a home, office, etc. type setting). Forexample, wireless terminals WT-A 102 and WT-B 106 may establish a firstpeer-to-peer network 108 and wireless terminals WT-B 106 and WT-C 112may also establish a second peer-to-peer network 114.

Additionally, each peer-to-peer network connection 108 and 114 mayinclude wireless terminals within a similar geographic area (e.g.,within range of one another). However, it is to be appreciated thatwireless terminals need not be associated with the same sector and/orcell to be included in a common peer-to-peer network. Further,peer-to-peer networks may overlap such that one peer-to-peer network maytake place within a region that overlaps or is encompassed with anotherlarger peer-to-peer network. Additionally, a wireless terminal may notbe supported by a peer-to-peer network. Wireless terminals may employthe wide area network and/or the peer-to-peer network where suchnetworks overlap (e.g., concurrently or serially). Moreover, wirelessterminals may seamlessly switch or concurrently leverage such networks.Accordingly, wireless terminals whether transmitting and/or receivingmay selectively employ one or more of the networks to optimizecommunications.

Peer-to-peer communications between the wireless terminals may besynchronous. For example, wireless terminals WT-A 102 and WT-B 106 mayutilize a common clock reference to synchronize performance of distinctfunctions. The wireless terminals WT-A 102 and WT-B 106 may obtaintiming signals from the access node AN-A 104. The wireless terminalsWT-A 102 and WT-B 106 may also obtain timing signals from other sources,for instance, GPS satellites or television broadcast stations. Accordingto an example, time may be meaningfully partitioned in a peer-to-peernetwork for functions such as peer discovery, paging, and traffic.Further, it is contemplated that each peer-to-peer network may set itsown time.

Before communication of traffic in a peer-to-peer connection can takeplace, the two peer wireless terminals may detect and identity eachother. The process by which this mutual detection and identificationbetween peers takes place may be referred to as peer discovery. Thecommunication system 100 may support peer discovery by providing thatpeers, desiring to establish peer-to-peer communications, periodicallytransmit short messages and listen to the transmissions of others. Forexample, the wireless terminals WT-A 102 (e.g., transmitting wirelessterminal) may periodically broadcast or send signals to the otherwireless terminal(s) WT-B 106 (e.g., receiving wireless terminal(s)).This allows the receiving wireless terminal WT-B 106 to identify thesending wireless terminal WT-A 102 when the receiving wireless terminalWT-B 106 is in vicinity of the sending wireless terminal WT-A 102. Afteridentification, an active peer-to-peer connection 108 may beestablished.

Transmissions for peer discovery may periodically occur during specifiedtimes referred to as peer discovery intervals, the timing of which maybe predetermined by a protocol and known to the wireless terminals WT-A102 and WT-B 106. Wireless terminals WT-A 102 and WT-B 106 may eachtransmit respective signals to identify themselves. For example, eachwireless terminal WT-A 102 and WT-B 106 may send a signal during aportion of a peer discovery interval. Further, each wireless terminalWT-A 102 and WT-B 106 may monitor signals potentially transmitted byother wireless terminals in a remainder of the peer discovery interval.According to an example, the signal may be a beacon signal. By way ofanother illustration, the peer discovery interval may include a numberof symbols (e.g., OFDM symbols). Each wireless terminal WT-A 102 mayselect at least one symbol in the peer discovery interval fortransmission by that wireless terminal WT-A 102. Moreover, each wirelessterminal WT-A 102 may transmit a corresponding signal in one tone in thesymbol selected by that wireless terminal WT-A 102.

The local area peer-to-peer network and the wide area network may sharea common wireless spectrum to effectuate communication; thus, bandwidthmay be shared for transferring data via the disparate types of networks.For example, the peer-to-peer network and the wide area network may bothcommunicate over the licensed spectrum. However, the peer-to-peercommunication need not utilize the wide area network infrastructure.

After wireless terminals discover each other, they may proceed toestablish connections. In some examples, a connection links two wirelessterminals, e.g., in FIG. 1 connection 108 links wireless terminals WT-Aand WT-B. Terminal WT-A 102 can then transmit traffic to terminal WT-B106 using connection 108. Terminal WT-B 106 can also transmit traffic toterminal WT-A 102 using connection 108.

FIG. 2 illustrates one example of a timing sequence for a trafficchannel slot that may be used by wireless terminals to transport trafficafter a peer-to-peer communication connection has been establishedbetween wireless terminals. Each traffic channel slot 210 may include atraffic management channel 201 and a traffic channel 203. The trafficmanagement channel 201 may be used for signaling related to traffic datatransmissions in the traffic channel 206. A connection schedulingsegment 202, a rate scheduling segment 204, and an acknowledgmentsegment 208 are collectively referred to as the traffic managementchannel 201. A data transmission segment 206 may be referred to as thetraffic channel 203. The connection scheduling segment 202, the ratescheduling segment 204, the data segment 206 and the acknowledgment 208shown in FIG. 2 comprise a traffic slot.

The connection scheduling segment 202 may be used by a transmitterterminal to indicate to its receiver terminal (in a peer-to-peerconnection) to indicate that it is ready to transmit traffic data. Therate scheduling segment 204 allows the transmitter/receiver terminals(in the peer-to-peer connection) to obtain a transmission rate and/orpower to use in transmitting the traffic data. The data transmissionsegment 206 is then used to transmit the desired traffic data at theobtained transmission rate and/or power. The acknowledgement segment 208may be used by the receiver terminal to indicate that the traffic datawas received or not received in the data transmission segment 206. Inone example, the time duration of a traffic slot is approximately two(2) milliseconds. As the traffic slots 210 repeat over time, the timesequence structure shown in FIG. 2 shows one period of the trafficslots. Note that, prior to sending traffic data in the traffic slot 210,the transmitter and receiver terminals may have established apeer-to-peer connection via a control slot 404 (in FIG. 4).

Collision Mitigation Using Transmission CIDs

In an ad hoc peer-to-peer communication system, multiple communicationsmay take place using frequency spectrum resources shared in both spaceand time. Because of the distributed nature of the ad hoc peer-to-peernetwork, it may not always be possible to control the channelallocations (e.g., slots) used for transmissions between the wirelessterminals. In wireless networks where a central authority does notexist, interference avoidance and/or management is a key feature tomaintain the efficiency of the network performance.

FIG. 3 is a block diagram illustrating an environment in which aplurality of wireless terminals may establish peer-to-peer communicationconnections that may cause interference to other nearby wirelessterminals. A peer-to-peer network 300 may include a plurality ofwireless terminals that may share and/or concurrently use a frequencyspectrum. The shared frequency spectrum may include one or moretransmission and/or control channels, with each transmission (traffic)channel having a corresponding traffic management channel. In oneexample, the traffic management channel may be used to send a trafficrequest for communications over a corresponding transmission (traffic)channel.

In one example, a first wireless terminal WT A 302 may be attempting totransmit 310 to a second wireless terminal WT B 304 while a thirdwireless terminal WT C 306 is concurrently attempting to transmit 314 toa fourth wireless terminal WT D 308 using the same traffic channelbandwidth resource. The first wireless terminal WT A 302 may be referredto as the intended transmitter, the second wireless terminal WT B 304may be referred to as the intended receiver, and the third wirelessterminal WT C 306 may be considered the interferer. In this peer-to-peernetwork 300, a transmission and control channel pair may be shared bythe plurality of the wireless terminals WT A, WT B, WT C, and WT D.However, because such transmission (traffic) and/or control channel isshared (e.g., frequency spectrum sharing) by the wireless terminals, itmay also result in unwanted interference 314′ and 310′ among thewireless terminals. For instance, if both transmissions 310 and 314actually take place, then the signal 314′ from the third wirelessterminal WT C 306 may be seen as interference to the second wirelessterminal WT B 304 receiver and may degrade its ability to successfullyrecover the desired signal 310 from the first wireless terminal WT A302. Therefore, certain interference management protocol is needed tomanage interference from the third wireless terminal WT C 306 to thesecond wireless terminal WT B 304. One goal of the interferencemanagement protocol is to allow the third wireless terminal WT C 306 totransmit without creating excessive interference to the second wirelessterminal WT B 304, thereby increasing the overall throughput andimproving the system performance. Note that in the meantime, the firstwireless terminal WT A 302 may also cause interference 310′ to thefourth wireless terminal WT D 308, and a similar interference managementprotocol may also be used to control that interference.

Because there is no centralized traffic management authority, there is achance that WT A 302 and WT C 306 may transmit on the same oroverlapping channel, thereby causing interference with each other. Forexample, by coincidence, both WT A 302 and WT C 306 may use the sametransmission CID. A transmission CID may be used to indicate aparticular transmission channel (e.g., frequency or time slot) to areceiving terminal WT B 304 and 308. Consequently, when the sametransmission CID is used by two terminals, they may also be concurrentlytransmitting on the same channel or overlapping channels. If bothtransmitting terminals WT A 302 and WT C 306 are within range of thereceiver terminals WT B 304 and/or WT D 308, then the receiver terminalsWT B 304 and/or WT D 308 may perceive interference.

In particular, a way is needed that allows multiple wireless terminalsto choose channels within shared frequency the without distinguishbetween transmissions from an intended peer and those from an unintendedpeer.

Channel Architecture

FIG. 4 illustrates one example of a channel architecture in which acontrol slot in inserted every so often between traffic slots. Trafficslots 402 are time intervals during which a transmitter terminal maysend peer-to-peer traffic data to a receiver terminal through thetransmission channel. In one example, each traffic slot 402 may be asillustrated in FIG. 2. Each traffic slot may be 2 milliseconds (ms)long. A traffic slot 402 may include a traffic channel portion in whichdata traffic is transmitted and a traffic management channel portion inwhich scheduling and interference management takes place.

Each control slot 404 may include a CID Broadcast Channel 406 and aPaging Channel 408. The control slot 404 may occur at much longerintervals than traffic slots. For instance, the control slot 404 mayoccur every second or so. A control slot 404 may serve to establish andmaintain a peer-to-peer connection between the transmitter and receiverterminals. The CID Broadcast Channel 406 may be used to indicate thosepeer-to-peer connection identifiers (CIDs) that are in use by nearbyconnections and to indicate whether a peer-to-peer connection is stillalive. For example, the transmitter and receiver terminals may monitorthe CID Broadcast Channel 406 to determine which CIDs are in use. ThePaging Channel 408 is used by the transmitter and receiver terminals toestablish new CIDs for a new peer-to-peer connection and may include aPaging Request Channel and a Paging Response Channel. The control slots404 may occur at much longer intervals than traffic slots 402. Forinstance, the control slots 404 may occur every second or so.

FIG. 5 illustrates an example time-frequency grid 500 associated with asignal transmission. The exemplary signal may be an OFDM signal. Thetime-frequency grid 500 is the resource available for transmittingand/or receiving signals over a peer-to-peer network, e.g., during acontrol slot (e.g., control slot 404 in FIG. 4) and/or traffic channelslot (traffic slot 210 in FIG. 2 within traffic management channel 201).The x-axis represents time and may include N symbols (e.g., where N maybe any integer), and the y-axis represents frequency and may include Mtones (e.g., where M may be any integer).

A transmitter and/or receiver terminal may use the time-frequency grid500 in the traffic management channel. For instance, the time-frequencygrid may be considered a CID resource space from which a terminal mayselect a CID resource unit corresponding to a CID. For example, in atraffic slot, a transmitter terminal may select a CID resource unit tosignal a transmission request to the corresponding receiver terminal ofthe connection associated with the CID. Similarly, the receiver terminalmay select a CID resource unit to signal a request response to thetransmitter terminal. The CID resource units available for thetransmitter terminal and for the receiver terminal may be partitioned apriori in a fixed manner so that the transmitter terminal selects a CIDresource unit in a fixed subset of the total time-frequency grid of thetraffic management channel, while the receiver terminal selects a CIDresource unit in a different fixed subset of the total time-frequencygrid of the traffic management channel. Such CID resource space may betransmitted, for example, in a control slot 404 (in FIG. 4) and/ortraffic slot 210 (in FIG. 2 within traffic management channel 201).

A CID resource unit may be defined by a time-frequency combination orsymbol-tone combination. According to an example, in a control slot or atraffic management portion of a traffic slot, a terminal may select aparticular symbol (e.g., transmission time) for transmission based uponan identifier of the wireless terminal or a user who is utilizing thewireless terminal and/or a time variable (e.g., time counter) that maybe commonly understood within a peer-to-peer network to identify thecurrent slot interval. Further, a particular tone corresponding to theselected symbol may be determined (e.g., based upon the identifierand/or time variable). Pursuant to a further example, a hash function ofthe identifier and the time variable may yield the selected symbolposition and/or tone position. For example, for a given connection, whenthe time variable takes a first value, the hash function may yieldsymbol x₁ and tone y₁ such that the wireless terminal transmits asingle-tone signal P₁ as shown in FIG. 5 as the CID resource unit. Whenthe time variable takes a second value, the hash function may yieldsymbol x₂ and tone y₂ such that the wireless terminal transmits asingle-tone signal P₂ as shown in FIG. 5 as the CID resource unit.

Collision Avoidance Using Orthogonal Transmission CIDs

One feature provides for generating transmission CIDs which are notlikely to collide with each other in a two-hop neighborhood.Interference mitigation may be facilitated by generating and maintainingan orthogonal set of transmission CIDs where each Tx/Rx terminal pairchooses a transmission or connection CID which is not used by others inits neighborhood so as to make it less likely of the possibility ofcollisions. That is, this feature of generating and maintaining anorthogonal set of transmission CIDs makes it less likely for two or moreTx/Rx terminal pairs to accidentally choose the same transmission CID.This is because if two Tx/Rx terminal pairs accidentally chose the sameCID and the two Tx/Rx terminal pairs are within the reach of each other,then it would bring confusion to both Tx/Rx terminal pairs and otherneighboring terminals, e.g., when the terminals carry out the operationof interference management using the traffic management channel. Thisproblem may become more severe when AR/AT communications are present inthe system together with the ad hoc communication pairs.

When a transmitter terminal wants to initiate communications with acertain neighboring receiver terminal, it first selects one or moretransmission CIDs which are not used in its neighborhood. In asynchronous wireless network, this can be achieved by introducing a CIDbroadcast period 604 in a slow time scale, e.g., once every second. Ingeneral, it makes sense to make the CID broadcast period the same as thepaging period 603, where terminals ping each other to start theconversation.

As used herein, the term “orthogonal” refers to CIDs that are selectedso as to ensure that others are not currently using the same CID. Suchorthogonal CID may be achieved by first checking the CIDs that are inuse by other connections (e.g., by monitoring a CID broadcast channel),selecting a CID that is unused or available, and switching CIDs if acollision is detected.

FIG. 6 illustrates one example of a timing sequence for a CID broadcastincluding a CID broadcast period 604, and a paging period 606. In theCID broadcast period 604, a terminal that has already had a CIDbroadcasts its CID so that other terminals in the vicinity become awarethat the particular CID has been occupied. After the CID broadcastperiod 604, a paging period 606 occurs. The paging period 606 mayinclude a paging request period 608 and a paging response period 610. Apaging initiator 612 (e.g., transmitter terminal WT A) sends a pagingrequest to the paging target 614 (e.g., receiver terminal WT B) in thepaging request period 608. The paging target 614 then sends a pagingresponse back to the paging initiator 612 in the paging response period610. One purpose of the paging request and response exchange is toestablish a connection between the paging initiator 612 and pagingtarget 614. The paging initiator and target select a connection ID (CID)to be used by the two terminals in the subsequent traffic slots forexchanging other control and/or data traffic. To avoid interferenceand/or CID collisions with other neighboring connections, it ispreferable that the CID selected by the paging initiator 612 and target614 is not currently occupied or used by other terminals.

Therefore, the paging initiator and the paging target monitor the CIDbroadcast period 604 in order to detect which CIDs are not occupied inthe vicinity. Note that a CID may be reused by different connections ingeographic locations remote from each other, i.e., spatial reuse. Todetermine whether a CID is occupied or not, the paging initiator 612and/or target 614 may monitor the signal corresponding to the CID in theCID broadcast period 604 and measure the signal strength. The paginginitiator 612 and/or target 614 may compare the signal strength with athreshold. The value of the threshold may be fixed, or determined as afunction of a measurement of the background noise. Alternatively, thepaging initiator and/or target may compare the strength of the signalcorresponding to the CID with the strength of the signals correspondingto other CIDs.

Note that the paging initiator 612 and the target 614 may independentlymonitor the CID broadcast period 604 and determine which CIDs are notoccupied in the vicinity. Because the radio frequency (RF) condition maybe different at the paging initiator and the target, the list ofavailable CIDs determined by the initiator or the target may bedifferent. In one embodiment, the paging initiator 612 may determine oneor more available CIDs based on its measurement during the CID broadcastperiod 604 and sends a list of available CIDs to the target in thepaging request period 608. The paging target 614 may determine one ormore available CIDs based on its measurement during the CID broadcastperiod 604, compare them with the list received in the paging requestperiod 608, and select one CID out of the list from the paging initiator612 to use. The selected CID is desirably the one that both the paginginitiator 612 and target 614 consider to be available. The paging target614 then informs the initiator 612 the selected CID in the pagingresponse period 610.

Whether or not a CID is considered available (i.e., not occupied) isbased on signal strength measurement in the CID broadcast period 604.The initiator 612 and/or target 614 may associate each available CIDwith some quality indicator, which indicates the extent to which theinitiator 612 or target 614 considers the CID available. For example, ifthe received signal strength corresponding to a first CID is less thanthat of a second CID, then the initiator 612 or target 614 may determinethat the first CID is “more” available than the second CID, which isreflected in the quality indictors associated with the first and thesecond CIDs. Furthermore, the initiator 612 may rank the available CIDsaccording to the associated quality indicator, and accordingly determinethe list to send to the target 614. The initiator 612 may also includethe quality indicator in the paging request message (sent in during thepaging request period 608).

In the case where the available CIDs proposed by the initiator 612 areall considered “occupied” by the target 614, rather than select one outof the list from the initiator (transmitter terminal), the target 614may further propose other CIDs to be used. A few iterations may takeplace between the initiator and the target (transmitter and receiverterminals) before the two terminals converge on the particular CID to beused.

It is appreciated that there are multiple ways of designing the CIDbroadcast period 604 since this happens in a slow time scale and theoverhead is of less a constraint.

FIG. 7 illustrates one example of a two-part CID broadcast structurewhere each part covers the whole transmission CID space. For example,assuming the transmission CID space spans from 1 to N, each CIDbroadcast resource A1 702 and A2 704 in FIG. 7 may have N degrees offreedom. For example, each of A1 and A2 may include X tones in Y OFDMsymbols, where N=X*Y. Suppose that a first and second terminals 712 and714 are associated with a connection 716 that has already had a CID.Suppose that the connection 716 was established when the first terminal712 pages the second terminal 714. That is, between the first and thesecond terminals 712 and 714, it is understood that the first terminal712 was the initiator and the second terminal 714 the target. Then thefirst terminal 712 transmits a first signal 706 in the tone of thesymbol corresponding to the CID of the connection 716 in resource A1702, while the second terminal 714 transmits a second signal 708 in thetone of the symbol corresponding to the CID of the connection 716 inresource A2 704. In an alternative implementation, the CID broadcastperiod may include a single resource (i.e., just Resource A1 702), inwhich case, the first and the second terminals 712 and 714 may taketurns to broadcast in the CID broadcast periods, e.g., according to afixed pattern (e.g., alternate even/odd periods or pseudo random). Thatis, in a first CID broadcast period, the first terminal 712 may transmiton the single resource (e.g., resource A1 702) and the second terminal714 listens, while on a second broadcast period, the second terminal 714may transmit on the same single resource (e.g., resource A1 702) whilethe first terminal 712 listens.

One reason that both terminals 712 and 714 need to send signals in theCID broadcast period is to allow other terminals in the vicinity to beaware that the CID 706 and/or 708 has been occupied. Another reason isfor one of the two terminals to monitor the presence of the otherterminal. In other words, if one terminal drops out, e.g., due tobattery failure, or because the distance between the two terminalsincreases beyond certain range, the CID broadcast period allows the twoterminals 712 and 714 to realize that the connection 716 needs to betore down and the CID resource unit (e.g., 706 and 708 in resources A1702) needs to be relinquished. For example, if the first terminal 712does not detect the CID broadcast signal 708 that needs to be sent bythe second terminal 714 in the second resource A2 704, for some periodof time, the first terminal 712 may conclude that the connection 716 isdown. Subsequently, the first terminal 712 relinquishes the CID 706 andno longer sends the CID broadcast signal 706 in the CID broadcastperiod. This allows the CID (and CID resource units at 706 and 708) tobecome available again and be selected by other terminals in thevicinity.

Note that when two terminals start a connection following the protocolshown in FIG. 6, the CID may be unoccupied in the vicinity. However, asthe RF condition changes, CID collision may still occur. For example,the two terminals may move to a new location where another pair ofterminals may also use a connection associated with the same CID. Usingthe design of the CID broadcast period in FIG. 7 may not detect such aCID collision easily.

FIG. 8 illustrates one example of a four-part CID broadcast structure toenable detection of CID collision. Similar to the resources A1 702 andA2 704 in FIG. 7, each resource covers the whole transmission CID space.Each transmission CID within the transmission CID space is defined (orassociated with) a particular tone/symbol or frequency-time thatcorresponds to a transmission traffic channel. For example, assuming thetransmission CID space spans from 1 to N, each CID broadcast resource A1802, A2 804, B1 806, and B2 808 may have N degrees of freedom. Similarto FIG. 7, in a connection between a first terminal 818 and a secondterminal 820, suppose that the first terminal 818 was the one thatinitiated the connection 822 (i.e., paging initiator) and the secondterminal 820 was the paging target. In one example, the first terminal818 is assigned to resources A1 802 and B1 804, while the secondterminal 820 is assigned to resources A2 806 and B2 808. Such assignmentof resources may be implied, where for example, the initiator terminalsknow that they should use resources A1 802 and B1 804 while the targetterminals know that they should use resources A2 806 and B2 808. Notethat different assignments of resources to the first and secondterminals 818 and 820 are also possible.

The first terminal 818 may select one of the two resources A1 802 and B1804 to send a signal corresponding to the CID of the connection 822between the first and the second terminals 818 and 820. The firstterminal 818 may then listen on the non-selected resource to determineif another terminal is using the same transmission CID. For example, thefirst terminal 818 may select to transmit a CID broadcast signal 810defined by a location (tone/symbol) within the CID space in resource A802, while listening at position 814 (i.e., resource unit) in resourceB1 804 for collisions. If the first terminal 818 detects that a CIDbroadcast signal is sent in position 814, the first terminal 818 mayconclude that another terminal may also be using the same CID, i.e., CIDcollision is detected. Similarly, the second terminal 820 may select oneof the two resources A2 806 and B2 808 to send a signal corresponding tothe CID of the connection 822 between the first and the second terminals818 and 820. For example, the second terminal 820 may select to transmita CID broadcast signal 812 defined by a location within the CID space inresource A2 806.

At any particular CID broadcast period, the selection of one resourceover another resource (e.g., between resources A1 and B1) may bepseudo-randomly determined as a function of terminal or device IDs ofthe first and/or second terminals. For example, the first terminal 818may use its device ID and a pseudo-random function to determine whichresource to select between resources A1 802 and B1 804, while the secondterminal 820 may use its device ID and the same pseudo-random functionto determine which resource to select between resources A2 806 and B2808. The selection may also be determined as a function of a timecounter. For instance, the first and the second terminals 818 and 820may derive the value of the time counter from a common timing source.This way, the selection varies as the time evolves.

In a preferred embodiment, the first terminal 818 knows which resource(either A2 or B2) the second terminal 820 will select between A2 806 andB2 808. This is possible because the first terminal 818 has theconnection 822 with the second terminal 820 and knows how the secondterminal 820 may select. For example, the second terminal 820 may selectto transmit a CID broadcast signal in resource A2 806. As described inFIG. 7, in order to check the presence of the second terminal 820, thefirst terminal 818 monitors to see whether a CID broadcast signal 812corresponding to the CID has been received in resource A2 806. If so,the first terminal 818 may conclude that the connection 822 is stillalive. No further action is needed. Otherwise, the first terminal 818may conclude that the connection 822 is lost and the first terminal 818may then tear down the connection 822 and relinquish the CID byrestraining from transmitting CID broadcast signals in positions 810 and814 corresponding to the CID. Moreover, the first terminal 818 monitorsto whether a CID broadcast signal 816 corresponding to the CID has beenreceived in resource B2 808. If so, the first terminal 818 may concludethat another terminal may also use the same CID, i.e., CID collision isdetected. The first terminal 818 may inform the second terminal 820 ofsuch ID collision so that their connection 822 may need to change to adifferent CID.

Note that, in one example, the first and second terminals 818 and 820may periodically, pseudo-randomly, or randomly select between theirresources A1 802, A2 804, B1 806, and B2 808. By periodically,pseudo-randomly, or randomly changing the resource used at a particulartime interval, the chances of detecting collision are improved. That is,while it may be possible that the first terminal and yet anotherterminal may select the same transmission CID in the same resource for aparticular time interval, it is less likely that they will continuallychoose the same resource when each independently selects between the tworesources every so often.

FIG. 9 (comprising FIGS. 9A and 9B) is a block diagram illustrating theuse of orthogonal transmission CIDs within a peer-to-peer communicationconnection between terminals. In establishing a peer-to-peercommunication connection, a first terminal WT A 902 and a secondterminal WT B 904 may utilize a CID broadcast period as illustrated inFIGS. 6, 7 and 8. During a CID broadcast period 908, neighboringterminals that currently have active connections indicate the CIDs theyare using by sending a tone at a symbol (in a selected CID broadcastresource) corresponding to their selected transmission CID 910. Thefirst terminal WT A 902 and second terminal WT B 904 may monitor the CIDbroadcast(s) (e.g., CID broadcast resources) to determine which CIDs areused by others 912 and 914. Each terminal WT A 902 and WT B 904 may thenindependently create lists of the detected used transmission CIDs 916and 918. Note that due to the difference in their respective RFconditions, the two lists may be different since one terminal may beable to detect some used transmission CIDs that the other terminal doesnot. The terminals WT A 902 and WT B 904 may then exchange their listsof detected transmission CIDs 919, for example, during the paging period917 (also illustrated in FIG. 6).

During a paging period 917 (shown in FIG. 6), the terminals WT A 902 andWT B 904 may select an unused transmission CID in the CID broadcastresource structure 920 and 922. The first terminals 902 may also selecta first and second CID broadcast resources 921, where one of the two CIDbroadcast resources can be used to transmit a CID broadcast signal whilethe other may be used to monitor for CID collisions. Similarly, thesecond terminal 904 may also select a third and fourth CID broadcastresource 923, where one of the two CID broadcast resources can be usedto transmit a CID broadcast signal while the other may be used tomonitor for CID collisions.

Having selected a transmission CID for their peer-to-peer connection,during a traffic management period 926, the first wireless terminal WT A902 may then transmit a transmission request to the second terminal WT B904, using a dedicated channel resource, e.g., a particular tone in anOFDM symbol, in the traffic management channel period corresponding tothe selected CID (as shown 1614 in FIG. 16). For instance, theTransmission request may utilize a CID broadcast signal in a selectedCID slot of the first CID broadcast resource 928. Upon receiving thistransmission request, the second terminal WT B 904 then sends a requestresponse, again using a dedicated channel resource, e.g., a particulartone in an OFDM symbol, in the traffic management channel periodcorresponding to the selected CID (as shown 1616 in FIG. 16). Forinstance, the request response may utilize a CID broadcast signal in aselected CID slot of the third CID broadcast resource 930.

In a subsequent CID broadcast period 931, the first and second terminals902 and 904 may indicate to others that the selected CID is being used.For instance, the first terminal WT A 902 may send a CID broadcastsignal in the CID slot of either the first or second CID broadcastresource to inform to the second terminal WT B 904 that the connectionis still alive. The second terminal WT B 904 may also send a CIDbroadcast signal in the CID slot of either the third or fourth CIDbroadcast resource to inform to the first terminal WT A 902 that theconnection is still alive.

Additionally, the first and second terminals WT A 902 and WT B 904 maymonitor the CID broadcast resources to determine whether a collisionexists with the selected CID 932 and 934; i.e., to determine if anotherterminal has selected the same transmission CID.

If a CID collision is detected, the first and second terminals WT A 902and WT B 904 may negotiate to change their CID 940 during a subsequentpaging period 939.

Method for Collision Avoidance

FIG. 10 illustrates a method operational in a first device for avoidingchannel collisions and interference in peer-to-peer networks. A firstconnection identifier is selected for a peer-to-peer communicationconnection between the first device and a second device in a wirelesscommunications network 1000. Prior to sending the first connectionidentifier broadcast signal, the first device may select one of aplurality of symbols of a connection identifier broadcast channel in atime interval in which to send the first connection identifier broadcastsignal 1002.

The first device then sends a first connection identifier broadcastsignal corresponding to the first connection identifier in a connectionidentifier broadcast channel 1004. For instance, the first connectionidentifier broadcast signal may be sent in the selected symbol of theconnection identifier broadcast channel within the time interval. Thefirst device then monitors the connection identifier broadcast channelto determine whether the first connection identifier is being utilizedby another connection in the proximity 1006. As used herein, aconnection is in the “proximity” if it may be detected by the firstdevice, if the peer terminals utilizing such connection are within radiorange of the first device, or if it may cause interference above anacceptable threshold to the connection of the first device. If theconnection identifier is not being utilized by another device (foranother connection), then the first device may continue to use the firstconnection identifier 1018 for its peer-to-peer connection with thesecond device.

Otherwise, if it is determined that the first connection identifier isbeing utilized by another connection (another device) in the proximity1008, the first device monitors a connection identifier broadcastchannel corresponding to a second connection identifier to determinewhether the second connection identifier is being utilized by otherconnections (devices) in the proximity 1010. If the second connectionidentifier is not being utilized by another connection (or anotherdevice) 1012, the first device switches to the second connectionidentifier 1014. Otherwise, if the second connection identifier is beingused by another connection or device, another unused connectionidentifier may be selected 1016 by monitoring the connection identifierbroadcast channel for unused identifiers.

The first and second connection identifiers may belong to apredetermined set of a plurality of connection identifiers. For example,the first and second connection identifiers may be selected from theunused or available transmission CIDs in a CID broadcast resourcestructure, such as illustrated in FIGS. 7 and 8 for example.

In one example, the first device may receive a broadcast signal from acommon network timing source. For example, this common network timingsource may be derived from a WAN signaling or beacons. The value of atime counter can then be determined as a function of the receivedbroadcast signal and changes from one time interval to another timeinterval. The selected symbol (in step 1002) may be selected as afunction of the value of the time counter. Each of the plurality ofsymbols (in step 1002) may be an OFDM symbol including a plurality oftones, and the first connection identifier broadcast signal is sent inone of the plurality of tones in the selected symbol.

In one example, the combination of a selected OFDM symbol and tone maybe determined as a function of the first connection identifier, where adifferent connection identifier corresponds to a different combinationof selected OFDM symbol and tone. A plurality of OFDM symbols may beassociated with the first connection identifier. The selected symbol maybe selected from the plurality of OFDM symbols being associated with thefirst connection identifier as a function determined by both the firstand the second devices.

The second connection identifier broadcast signal may be received in theremaining OFDM symbols of the plurality of OFDM symbols being associatedwith the first connection identifier.

FIG. 11 illustrates a method for determining whether a connectionidentifier is or is not being used by another connection within apeer-to-peer network. In one example, the connection identifierbroadcast channel may include a plurality of symbols in a time interval.As with the example of FIG. 10, a first device may select a firstconnection identifier for a peer-to-peer communication connectionbetween the first device and a second device 11100. One of the pluralityof symbols within a time interval of the connection identifier broadcastchannel may be selected for, or associated with, the first connectionidentifier 1102. The first device may then send a first connectionidentifier broadcast signal corresponding to the first connectionidentifier in a connection identifier broadcast channel 1104.

Subsequently, the first device may listen on the connection identifierbroadcast channel to receive or detect a signal in the remaining symbolsof the connection identifier broadcast channel in the time interval1106. The first device may monitor for the presence (or absence) of asecond connection identifier broadcast signal in the received signal,wherein the second connection identifier broadcast signal corresponds tothe first connection identifier 1108. If the presence of the secondconnection identifier broadcast signal is detected the first device maymeasure the signal strength of the detected second connection identifierbroadcast signal 1110.

The first device may determine whether the first connection identifieris being utilized by other connections in the proximity in a number ofways. For example, if the second connection identifier broadcast signalis present in the received signal, the first device may assume thatanother connection is also utilizing the first connection identifier. Inanother example, if the signal strength of the second connectionidentifier broadcast signal in the received signal is above a firstthreshold, the first device may assume that another connection is alsoutilizing the first connection identifier. In yet another example, ifthe ratio of the signal strength of the second connection identifierbroadcast signal and the signal strength of a connection identifierbroadcast signal corresponding to another connection identifier in thereceived signal is above a second threshold, the first device may assumethat another connection is also utilizing the first connectionidentifier.

FIG. 12 is a block diagram illustrating another use of orthogonaltransmission CIDs within a peer-to-peer communication connection betweenterminals. In establishing a peer-to-peer communication connection, afirst terminal WT A 1202 and a second terminal WT B 1204 may utilize aCID broadcast period as illustrated in FIGS. 6, 7 and 8. The CIDbroadcast may be implemented within connection identifier broadcastchannel that includes a plurality of symbols in a time interval. Asymbol may be used to represent a CID or connection identifier. Othernearby terminals may broadcast their used CIDs in connection identifierbroadcast channel for connection identifier broadcast signals 1210. Thefirst wireless terminal WT A 1202 and second wireless terminals WT B1204 may monitor the connection identifier broadcast channel forconnection identifier broadcast signal 1212 and 1214. Based on thereceived connection identifier broadcast signals, the first wirelessterminal WT A 1202 and second wireless terminals WT B 1204 may eachcreate their own list of detected used transmission CIDs 1216 and 1218and exchange their list in order to select a connection identifier for apeer-to-peer communication connection between the first device and asecond device 1220.

A first symbol is then selected from the plurality of symbols of theconnection identifier broadcast channel in the time interval for thefirst terminal 1202 to send a first connection identifier broadcastsignal 1222. Similarly, a second symbol may be selected from theplurality of symbols for the first terminal 1202 to receive the secondconnection identifier broadcast signal 1224, which is to be transmittedby the second terminal 1204. The first and the second terminals 1202 and1204 may have a connection associated with the CID. The first and secondconnection identifier broadcast signals correspond to the same CID. Thefirst terminal 1202 is supposed to transmit the first CID broadcastsignal while the second terminal 1204 is supposed to transmit the secondCID broadcast signal. The first terminal 1202 monitors the presence ofthe second CID broadcast signal to see whether the connection is stillalive. If the second CID broadcast signal is received, e.g., withsufficient signal strength, then the first terminal may conclude theconnection is alive. Otherwise, the first terminal 1202 may conclude theconnection needs to be torn down. In one example, the first terminal1202 may need to detect several occurrences of the absence of the secondCID broadcast signals before it makes such a conclusion.

The first wireless terminal WT A 1202 may then send the first connectionidentifier broadcast signal in the connection identifier broadcastchannel 1226. The first terminal WT A 1202 may then monitor theconnection identifier broadcast channel to determine whether a secondconnection identifier broadcast signal corresponding to the CID isreceived 1228.

If the second connection identifier broadcast signal is not detected,the first terminal WT A 1202 may drop the connection with the secondterminal WT B 1230 and restrains from subsequently sending connectionidentifier broadcast signals corresponding to the connection identifierin the connection identifier broadcast channel 1232.

FIG. 13 illustrates a method of operating a first device for maintaininga connection identifier for a peer-to-peer communication connectionbetween the first device and a second device in a wirelesscommunications network. A connection identifier is selected for apeer-to-peer communication connection between the first device and asecond device 1300. A connection identifier broadcast channel mayinclude a plurality of symbols in a time interval. The first device,alone or in conjunction with the second device, may select a firstsymbol from the plurality of symbols of the connection identifierbroadcast channel in the time interval to send the first connectionidentifier broadcast signal 1301. The first device, alone or inconjunction with the second device, may also select a second symbol fromthe plurality of symbols to receive the second connection identifierbroadcast signal 1302. The first device then sends a first connectionidentifier broadcast signal corresponding to the connection identifierin a connection identifier broadcast channel 1304. The connectionidentifier broadcast channel may be monitored to determine whether asecond connection identifier broadcast signal corresponding to theconnection identifier is received from the second device 1306.

If the second connection identifier broadcast signal is not received1308, the second device is considered absent 1310. Consequently, thefirst device may drop the connection with the second device 1312 andrestrain from sending connection identifier broadcast signalscorresponding to the connection identifier in the connection identifierbroadcast channel 1314. Otherwise, if the second connection identifierbroadcast signal is received 1308, the first device may send/receivetraffic signal on traffic channel associated with the connectionidentifier 1316.

The first and second selected symbols may be selected as a function ofthe connection identifier. The selection of the first and second symbolsmay be determined jointly or individually by the first and seconddevices. Each of the plurality of symbols may be an OFDM symbolincluding a plurality of tones, said first connection identifierbroadcast signal is sent in one of the plurality of tones in the firstselected symbol, and said second connection identifier broadcast signalis received in one of the plurality of tones in the second selectedsymbol. The combinations of selected OFDM symbol and tone of the firstand the second connection identifier broadcast signals may be determinedas a function of the connection identifier, and different connectionidentifiers correspond to different combinations of selected OFDM symboland tone. The first and the second selected OFDM symbols may be at leastone OFDM symbol apart.

The connection identifier broadcast channel includes at least a firstand a second predetermined subsets of OFDM symbols, the first selectedOFDM symbol in which the first connection identifier broadcast signal issent belongs to the first subset, and the second selected OFDM symbol inwhich the second connection identifier broadcast signal is receivedbelongs to the second subset. The partition of the first and secondsubsets may be independent of any connection identifier.

FIG. 14 is a block diagram illustrating another use of orthogonaltransmission CIDs within a peer-to-peer communication connection betweenterminals. In establishing a peer-to-peer communication connection, afirst terminal WT A 1402 and a second terminal WT B 1404 may utilize aCID broadcast period as illustrated in FIGS. 6, 7 and 8. The CIDbroadcast may be implemented within connection identifier broadcastchannel that includes a plurality of symbols in a time interval. Asymbol may be used to represent a transmission CID or connectionidentifier. A CID is associated with a connection between the first andthe second terminals 1402 and 1404.

A connection identifier is selected by the first device WT A 1402 from apredetermined set of a plurality of connection identifiers 1408. Thefirst device WT A 1402 sends a paging request message to the seconddevice WT B 1404 including control information indicative of theselected connection identifier 1410. The first terminal 1402 may includeone or more selected connection identifiers in the paging requestmessage. The first terminal 1402 selects one connection identifier if itis determined that the connection identifier is not currently used oroccupied by other connections in the proximity. To do this, the firstterminal 1402 may monitor the CID broadcast period, as shown in FIG. 7or FIG. 8, to determine whether a particular CID is occupied, e.g., bymeasuring the strength of the CID broadcast signal corresponding to theCID. Meanwhile, the second terminal 1404 may also determine the list ofunoccupied CIDs based on its own measurement of the CID broadcastperiod. Upon receiving the proposed list of selected connectionidentifiers from the first terminal, the second device WT B 1404 maycompare the list from the first terminal with its own list to determinewhether a CID can be selected that is considered unoccupied from theperspective of both the first and the second terminals. If so, thesecond terminal WT B 1404 responds to the first terminal 1402 to includethe selected CID in the paging response message.

After the two devices have established the connection and the associatedCID, they can further exchange control and data traffic. For example,the first device WT A 1402 then transmits a transmission request signalto the second device WT B 1404 using a first transmission resource unit1414. The first transmission resource unit may include a subset of tonesin a subset of symbols within a traffic management channel slot and thefirst transmission resource unit may be determined as a function of theconnection identifier. For instance, the first device WT A 1402 maytransmit on a selected symbol/tone combination (associated with theconnection identifier) in Resource A 1610 in FIG. 16.

The first device WT A 1402 also monitors a second transmission resourceunit corresponding to the first transmission resource unit to determinewhether a request response signal is received from the second device1404 in the second transmission resource unit 1416. The secondtransmission resource unit may be a subset of tones in a subset ofsymbols within the traffic management channel slot. For instance, thefirst device WT A 1402 may monitor on a selected symbol/tone combination(associated with the connection identifier) in Resource B 1612 in FIG.16.

Upon receiving the transmission request, the second device WT B 1404sends a request response signal to the first device WT A 1402 using thesecond transmission resource 1418. For instance, the second device WT B1404 may send the request response signal on the selected symbol/tonecombination (associated with the connection identifier) in Resource B1612 in FIG. 16.

If the first device WT A 1402 receives the request response 1418, it maytransmit traffic data to the second device WT B 1404 in a trafficchannel slot corresponding to the traffic management channel slot 1420(i.e., associated with the connection identifier).

FIG. 15 illustrates a method operational in a first device for selectingand utilizing a connection identifier for a peer-to-peer communicationconnection between the first device and a second device in a wirelesscommunications network. A broadcast signal is received from a commonnetwork timing source 1500. For instance, a WAN in which the first andsecond devices operate may provide beacons from which the common networktiming can be ascertained. The value of a time counter may be determinedas a function of the received broadcast signal. The first and secondtransmission resource units in the traffic management channel aredetermined as a function of the value of the time counter 1502, as wellas the CID of the connection between the first and the second terminals.A “transmission resource unit” may be particular symbol/tone combinationwithin the traffic management channel. For example, tone/symbol 1614 and1616 in both Resources A 1610 and B 1612 in FIG. 16, may be determinedor selected as a function of the value of the time counter and the CID.

The connection identifier is selected from a predetermined set of aplurality of connection identifiers 1504. A connection identifierbroadcast channel may be previously monitored to determine whether theconnection identifier is being utilized by other connections in theproximity. The connection identifier is selected only if it isdetermined that the connection identifier is not being utilized byanother connection in the proximity.

To determine whether the connection identifier is not being utilized byother connections in the proximity, the first device may detect thepresence (or absence) of a connection identifier broadcast signal in theconnection identifier broadcast channel, the connection identifierbroadcast signal corresponding to the connection identifier. If thepresence of the connection identifier broadcast signal is detected, thefirst device may measure the signal strength of the connectionidentifier broadcast signal. The first device may determine that theconnection identifier is not being utilized by other connections in theproximity if either (a) the connection identifier broadcast signal isnot present, (b) the signal strength of the connection identifierbroadcast signal is below a first threshold, or (c) the ratio of thesignal strength of the connection identifier broadcast signal and thesignal strength of a connection identifier broadcast signalcorresponding to another connection identifier is below a secondthreshold.

Each of the predetermined set of a plurality of connection identifiersmay correspond to a unique combination of tone and OFDM symbol in atraffic management channel slot to be used as either the first or secondtransmission resource units. For a given value of the time counter,first transmission resource units determined by different connectionidentifiers may be orthogonal with each other (i.e., two differentconnection identifiers correspond to two distinct transmission resourceunits) and second transmission resource units determined by differentconnection identifiers may be orthogonal with each other.

A control message may be sent by the first device to the second deviceindicating the selected connection identifier 1506. In one example, thecontrol message may be a paging request message indicating that thefirst device intends to establish a connection with the second device inwhich the first device proposes to use the selected connectionidentifier to identify the connection. In another example, the controlmessage may be a paging response message responding to a paging requestmessage received from the second device, where the paging responsemessage may indicate that the first device agrees to establish aconnection with the second device and that the first device proposes touse the selected connection identifier to identify the connection.

After the connection has been established between the first and thesecond devices and the CID has been selected, the CID can be used toschedule data and control traffic between the two devices. For example,in a subsequent traffic slot, a transmission request signal istransmitted from the first device to the second device using a firsttransmission resource unit, the first transmission resource unit being asubset of tones in a subset of symbols within a traffic managementchannel slot and the first transmission resource unit being determinedas a function of the connection identifier 1508. A second transmissionresource unit corresponding to the first transmission resource unit ismonitored to determine whether a request response signal is receivedfrom the second device in the second transmission resource unit, thesecond transmission resource unit being a subset of tones in a subset ofsymbols within the traffic management channel slot 1510. The secondtransmission resource unit may also be determined as a function of theconnection identifier.

The first device then determines if a request response signal isreceived from the second device 1512. If so, traffic data is transmittedto the second device in a traffic channel slot corresponding to thetraffic management channel slot 1514. Otherwise, if no request responsesignal is received, the first device does not transmit traffic data tothe second device using the selected connection identifier 1516.

The traffic management channel slot may include a plurality of OFDMsymbols, each OFDM symbol including a plurality of tones, and each ofthe first and second transmission resource units may include at leastone tone in one of the plurality of symbols in the traffic managementchannel slot. A different connection identifier may correspond to adifferent tone and OFDM symbol combination in the traffic managementchannel slot to be used as either the first or second transmissionresource units.

Illustration of Traffic management Channel Using Orthogonal CIDs

FIG. 16 is a diagram illustrating the traffic management channel usingorthogonal CIDs. In this example, a first device WT A 1602 and a seconddevice WT B 1604 have established a peer-to-peer connection associatedwith a first CID, while a third device WT C 1606 and a fourth device WTD 1608 have established another peer-to-peer connection associated witha second CID, which is different from the first CID.

A traffic slot as shown in FIG. 2 includes a traffic management channelperiod and a traffic channel period. In particular, the connectionscheduling portion of the traffic management channel period is used tomanage traffic interference between the two connections. In oneembodiment, the connection scheduling portion includes resources A 1610and B 1612. In each of resources A and B, there is a plurality ofsymbols, each symbol including a number of tones. Each small box inresources A and B represents a basic transmission resource unit, whichis a tone over one symbol, e.g., OFDM symbol.

The connection of the first CID has a reserved transmission resourceunit in both resources A and B. The two transmission resource units aredetermined by the first CID of the connection between WT A and WT B.Similarly, the connection of the second CID has a reserved transmissionresource unit in both resources A and B. The two transmission resourceunits are determined by the CID of the connection between WT C and WT D.In a preferred embodiment, connections of different CIDs correspond todifferent reserved transmission resource units. In this sense, the CIDsare orthogonal with each other.

First device WT A 1602 can transmit a transmission request signal usingthe reserved transmission resource unit 1614 to indicate its intensionto send traffic to second device WT B 1604. Second device WT B 1604 canthen transmit a request response using the reserved transmissionresource unit 1616 to indicate its intension to receive traffic from thefirst device WT A 1602, if it is so determined. After transmitting thetransmission request, first device WT A 1602 monitors to determinewhether the second device WT B 1604 has transmitted a request response.If so, the first device WT A 1602 proceeds to send traffic in thecorresponding traffic channel period of the current traffic slot.Clearly, if the two connections happen to use the same CID, theterminals of both connections tend to believe that the transmissionresource units are reserved for the exclusive by them. This will lead toerroneous operation. For example, after WT A 1602 transmits atransmission request using the reserved transmission resource unit, bothWT B 1604 and WT D 1608 will think that the request signal is sent by WTA 1602 and WT C 1606 respectively. Such confusion will lead to adversesystem operations. Thus, it is important to avoid and detect CIDcollision.

If interference is perceived by a device, it may negotiate a differenttransmission CID (symbol/tone combination in Resources A and B) to usefor its peer-to-peer connection.

Wireless Terminal Configured to Use Orthogonal Transmission CIDs in P2PConnection

FIG. 17 is a block diagram illustrating an example of a wirelessterminal that may be configured to perform orthogonal transmission CIDselection in a peer-to-peer network. The wireless terminal 1702 maycommunicate directly with substantially any number of disparate wirelessterminals 1720 over peer-to-peer connections.

Wireless terminal 1702 may include a peer discovery communicator 1704that may effectuate encoding, sending, receiving, evaluating, of signalsassociated with peer discovery during a peer discovery interval (or aplurality of peer discovery intervals). Peer discovery communicator 1704may further comprise a signal generator 1706 and a peer analyzer 1708.The signal generator 1708 may generate and/or transmit a signal todisparate wireless terminals 1720 via wireless peer-to-peer connections1710 and those wireless terminals may evaluate the signal to detect andidentify wireless terminal 1702. Further, peer analyzer 1708 may receivesignal(s) sent from disparate wireless terminal(s) 1720 and may evaluatethe received signal(s) to detect and identity disparate wirelessterminal(s) 1720 to which the received signal(s) correspond.

Wireless terminal 1702 may additionally include a synchronizer 1712 thatconforms timing between wireless terminal 1702 and the disparatewireless terminals 1720. Synchronizer 1712 may obtain its timing frombroadcast information (e.g., a common clock reference 1714) from a basestation (not shown) in a vicinity of wireless terminal 1702. Similarly,synchronizers of the disparate wireless terminals 1720 may obtain theirrespective timing from the same broadcast information (reference clock1714). The broadcast information may be, for example, a single-tonebeacon signal, a CDMA PN (pseudo random) sequence signal, a pilot signalor other broadcast signal. Synchronizer 1712 may evaluate the obtainedbroadcast information to determine timing information. By way ofillustration, wireless terminal 1702 and the disparate wirelessterminals 1720 may receive and synchronize to the same broadcastinformation, and therefore, have a common understanding of time. Thecommon notion of time may be utilized to partition a timeline intodistinct intervals for differing types of functions such as, forinstance, peer discovery, paging, and traffic, according to apredetermined pattern defined by an air interface protocol. Moreover,the timing information may be utilized by the signal generator 1706 tocreate signals for transmission during peer discovery and/or peeranalyzer 1708 to evaluate received signals for peer discovery.Furthermore, the synchronizer 1712 obtains and analyzes the common clockreference 1714 to coordinate performance of various functions (e.g.,peer discovery, paging, traffic) and determine a meaningful notion oftime (e.g., time counter) consistent with disparate wireless terminals1720 in the peer-to-peer network. Therefore, peers get the same timing(timing synchronized) without directly communicating with each other.

The wireless terminal 1702 may be associated with a unique identifier(WT ID). For example, wireless terminal 1702 may include memory 1716that retains a unique identifier (WT ID) that corresponds to wirelessterminal 1702. However, it is contemplated that wireless terminal 1702may derive, obtain, etc., its unique identifier (WT ID) from anylocation (e.g., local and/or remote to wireless terminal 1702).Additionally, memory 1716 may retain any additional type of data and/orinstructions related to wireless terminal 1702. Moreover, wirelessterminal 1702 may include a processor (not shown) that executesinstructions described herein.

Signal generator 1706 may create and/or transmit a signal to thedisparate wireless terminals 1720. Signal generator 1706 may encodeand/or send a signal in a peer discovery interval as a function of theunique identifier (WT ID) of wireless terminal 1702. In accordance withan example, the signal yielded by signal generator 1706 may be asingle-tone beacon signal, which may provide power efficiency. Thus,signal generator 1706 may effectuate transmitting a particular tone on aselected OFDM symbol within a peer discovery interval. It iscontemplated that more than one beacon signal may be transmitted (e.g.,in a plurality of OFDM symbols). For example, where the transmittedsignal is a beacon signal, a selected symbol time position (e.g., withinthe peer discovery interval) and/or a tone position may be derived by ahash function of the unique identifier of wireless terminal 1702 (WT ID)and a time variable (e.g., timing information obtained by synchronizer1712, time counter) identifying a current peer discovery interval.Further, wireless terminal 1702 and disparate wireless terminals 1720may have a common value of the time variable (e.g., due tosynchronization achieved by listening to an infrastructure communicationchannel available in a geographic area).

Pursuant to another example, the identifier associated with wirelessterminal 1702 (WT ID) may be broadcast to peer(s) by signal generator1706 (and/or peer discovery communicator 1704). Peer(s) obtaining thesignal may detect and/or identify wireless terminal 1702. For example,the signal yielded by signal generator 1706 may be an output of an M-bithash function whose input is the plain-text name of wireless terminal1702 (e.g., WT ID) and a current counter value supplied by a basestation broadcast signal (e.g., common clock reference). The countervalue, for instance, may be constant during a current peer discoveryinterval and may be decodable by all peers. The counter value may vary(e.g., increment in a modulo sense) from one peer discovery interval toanother. Further, the hash function may be specified a priori by aprotocol and known to the peers.

By way of example, wireless terminal 1702 may be located in apeer-to-peer network that includes disparate wireless terminal WT A, WTB and WT n 1720. Synchronizer 1712 may determine timing associated withpeer-to-peer communications (e.g., based upon a received common clockreference). Further, at a time partitioned for peer discovery, signalgenerator 1706 may broadcast a signal (e.g., generated based upon anidentifier (CID) of the originating wireless terminal 1702 and/or acurrent time) to disparate wireless terminals within range (e.g.,disparate wireless terminals 1720). The signal may be received andutilized by disparate wireless terminals 1720 to detect wirelessterminal 1702 and/or determine an identity of wireless terminal 1702.Moreover, peer analyzer 1708 may obtain broadcast signals from disparatewireless terminals 1720. Peer analyzer 1708 may evaluate the obtainedsignals to detect disparate wireless terminals 1720 and/or identifydisparate wireless terminals 1720.

Peer discovery effectuated by peer discovery communicator 1704 may bepassive. Further, peer discovery may be symmetric; thus, wirelessterminal 202 may detect and identify disparate wireless terminals WT A,WT B, and WT n 1720, and these disparate wireless terminals 1720 maydetect and identify wireless terminal 1702. However, it is contemplatedthat a first wireless terminal may detect and identify a second wirelessterminal, but the second wireless terminal may fail to detect andidentify the first wireless terminal. Additionally, upon detection andidentification, further communication (e.g., paging, traffic) betweenwireless terminal 1702 and disparate wireless terminal(s) 1720 may, butneed not, be effectuated.

Peer analyzer 1702 may maintain a list of disparate wireless terminals1720 that are detected to be present in the current time. The list mayinclude all disparate wireless terminals 1720 or may include those in apredefined buddy list of wireless terminal 1702 or the user who is usingwireless terminal 1702. As the time goes by, the list evolves, becausesome disparate wireless terminals 1720 may disappear (e.g., because thecorresponding users move away), or because other disparate wirelessterminals 1720 may appear (e.g., because the corresponding users moveclose). Peer analyzer 1708 may add the new disparate wireless terminals1720 to the list or delete disappearing disparate wireless terminals1720 from the list. In one embodiment, peer analyzer 1708 passivelymaintains the list. In this case, a first peer may detect the presenceof a second peer and keep the second peer in its list without informingthe second peer. As a result, the second peer may not know that thefirst peer has already kept the second peer in the list. By symmetry,depending on wireless channel and interference condition, the secondpeer may also detect the presence of the first peer and keep the firstpeer in its list without informing the first peer. In anotherembodiment, after the first peer detects the presence of the secondpeer, the first peer proactively sends a signal to inform the secondpeer so that the second peer now knows that the first peer has alreadykept the second peer in the list, even though the first peer has no datatraffic to communicate with the second peer yet. The first peer mayselectively decide whether it sends a signal. For example, the firstpeer may send a signal only to another peer that is in the predefinedbuddy list.

Additionally, the wireless terminal 1702 and components therein may beconfigured to perform one or more of the features illustrated in FIGS.1-16.

FIG. 18 is a block diagram of another embodiment of a wireless terminalthat may be configured to perform orthogonal transmission CID selectionin a peer-to-peer network. The wireless terminal 1802 may include aprocessing circuit (e.g., one or more circuits or processors), apeer-to-peer communication controller 1812, a wide area network (WAN)controller 1810 and a transceiver 1814 coupled to an antenna 1806. Thetransceiver 1814 may include a (wireless) transmitter and a (wireless)receiver. The wireless terminal 1802 may communicate via a managednetwork infrastructure using the WAN communication controller 1810and/or it may communicate over a peer-to-peer network using thepeer-to-peer communication controller 1812. When performing peer-to-peercommunications, the wireless terminal 1802 may be configured to performone or more of the features illustrated in FIGS. 1-16.

It will be appreciated that, in accordance with one or more aspectsdescribed herein, inferences can be made regarding discovering andidentifying peers in a peer-to-peer environment. As used herein, theterm to “infer” or “inference” refers generally to the process ofreasoning about or inferring states of the system, environment, and/oruser from a set of observations as captured via events and/or data.Inference can be employed to identify a specific context or action, orcan generate a probability distribution over states, for example. Theinference can be probabilistic—that is, the computation of a probabilitydistribution over states of interest based on a consideration of dataand events. Inference can also refer to techniques employed forcomposing higher-level events from a set of events and/or data. Suchinference results in the construction of new events or actions from aset of observed events and/or stored event data, whether or not theevents are correlated in close temporal proximity, and whether theevents and data come from one or several event and data sources.

According to an example, one or more methods presented above can includemaking inferences pertaining to identifying sources of peer discoverysignals in a peer-to-peer network. In accordance with another example,an inference may be made related to estimating a probability of a peerbeing located within proximity based upon a number of detected signalsthat match an expected signal format and/or energy levels associatedwith detected signals. It will be appreciated that the foregoingexamples are illustrative in nature and are not intended to limit thenumber of inferences that can be made or the manner in which suchinferences are made in conjunction with the various embodiments and/ormethods described herein.

One or more of the components, steps, and/or functions illustrated inFIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 and/or18 may be rearranged and/or combined into a single component, step, orfunction or embodied in several components, steps, or functions.Additional elements, components, steps, and/or functions may also beadded. The apparatus, devices, and/or components illustrated in FIGS. 1,3, 17 and/or 18 may be configured or adapted to perform one or more ofthe methods, features, or steps described in FIGS. 2, and/or 4-16. Thealgorithms described herein may be efficiently implemented in softwareand/or embedded hardware.

As used in this application, the terms “component,” “module,” “system,”and the like are intended to refer to a computer-related entity, eitherhardware, firmware, a combination of hardware and software, software, orsoftware in execution. For example, a component may be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, a program, and/or acomputer. By way of illustration, both an application running on acomputing device and the computing device can be a component. One ormore components can reside within a process and/or thread of executionand a component may be localized on one computer and/or distributedbetween two or more computers. In addition, these components can executefrom various computer readable media having various data structuresstored thereon. The components may communicate by way of local and/orremote processes such as in accordance with a signal having one or moredata packets (e.g., data from one component interacting with anothercomponent in a local system, distributed system, and/or across a networksuch as the Internet with other systems by way of the signal).

Furthermore, various embodiments are described herein in connection witha wireless terminal. A wireless terminal can also be called a system,subscriber unit, subscriber station, mobile station, mobile, mobiledevice, remote station, remote terminal, access terminal, user terminal,terminal, wireless communication device, user agent, user device, oruser equipment (UE). A wireless terminal may be a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, computing device,or other processing device connected to a wireless modem.

In the following description, specific details are given to provide athorough understanding of the configurations. However, it will beunderstood by one of ordinary skill in the art that the configurationsmay be practiced without these specific detail. For example, circuitsmay be shown in block diagrams in order not to obscure theconfigurations in unnecessary detail. In other instances, well-knowncircuits, structures and techniques may be shown in detail in order notto obscure the configurations.

Also, it is noted that the configurations may be described as a processthat is depicted as a flowchart, a flow diagram, a structure diagram, ora block diagram. Although a flowchart may describe the operations as asequential process, many of the operations can be performed in parallelor concurrently. In addition, the order of the operations may bere-arranged. A process is terminated when its operations are completed.A process may correspond to a method, a function, a procedure, asubroutine, a subprogram, etc. When a process corresponds to a function,its termination corresponds to a return of the function to the callingfunction or the main function.

In one or more examples and/or configurations, the functions describedmay be implemented in hardware, software, firmware, or any combinationthereof. If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by ageneral purpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code means in the form of instructions or datastructures and that can be accessed by a general-purpose orspecial-purpose computer, or a general-purpose or special-purposeprocessor. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above are also beincluded within the scope of computer-readable media.

Moreover, a storage medium may represent one or more devices for storingdata, including read-only memory (ROM), random access memory (RAM),magnetic disk storage mediums, optical storage mediums, flash memorydevices and/or other machine readable mediums for storing information.

Furthermore, configurations may be implemented by hardware, software,firmware, middleware, microcode, or any combination thereof. Whenimplemented in software, firmware, middleware or microcode, the programcode or code segments to perform the necessary tasks may be stored in acomputer-readable medium such as a storage medium or other storage(s). Aprocessor may perform the necessary tasks. A code segment may representa procedure, a function, a subprogram, a program, a routine, asubroutine, a module, a software package, a class, or any combination ofinstructions, data structures, or program statements. A code segment maybe coupled to another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters, or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

Those of skill in the art would further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the configurations disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system.

The various features described herein can be implemented in differentsystems. For example, the secondary microphone cover detector may beimplemented in a single circuit or module, on separate circuits ormodules, executed by one or more processors, executed bycomputer-readable instructions incorporated in a machine-readable orcomputer-readable medium, and/or embodied in a handheld device, mobilecomputer, and/or mobile phone.

It should be noted that the foregoing configurations are merely examplesand are not to be construed as limiting the claims. The description ofthe configurations is intended to be illustrative, and not to limit thescope of the claims. As such, the present teachings can be readilyapplied to other types of apparatuses and many alternatives,modifications, and variations will be apparent to those skilled in theart.

What is claimed is:
 1. A method operational in a first device forutilizing a first connection identifier for a peer-to-peer communicationconnection between the first device and a second device in a wirelesscommunications network, comprising: sending a first connectionidentifier broadcast signal corresponding to the first connectionidentifier in a connection identifier broadcast channel; monitoring theconnection identifier broadcast channel to determine whether the firstconnection identifier is being utilized by another connection in theproximity; and switching to a second connection identifier if it isdetermined that the first connection identifier is being utilized byanother connection in the proximity.
 2. The method of claim 1, whereinthe first and second connection identifiers belong to a predeterminedset of a plurality of connection identifiers.
 3. The method of claim 1,wherein the connection identifier broadcast channel includes a pluralityof symbols in a time interval, the first connection identifier broadcastsignal is sent in one of the symbols, and monitoring the connectionidentifier broadcast channel further comprising: receiving a signal inthe remaining symbols of the connection identifier broadcast channel inthe time interval; detecting the presence of a second connectionidentifier broadcast signal in the received signal, the secondconnection identifier broadcast signal corresponding to the firstconnection identifier; and measuring the signal strength of the detectedsecond connection identifier broadcast signal if the presence of thesecond connection identifier broadcast signal is detected.
 4. The methodof claim 3, wherein it is determined that the first connectionidentifier is being utilized by other connections in the proximity if itis determined that either the second connection identifier broadcastsignal is present in the received signal, or the signal strength of thesecond connection identifier broadcast signal in the received signal isabove certain threshold, or the ratio of the signal strength of thesecond connection identifier broadcast signal and the signal strength ofa connection identifier broadcast signal corresponding to anotherconnection identifier in the received signal is above certain threshold.5. The method of claim 3, further comprising: prior to sending the firstconnection identifier broadcast signal, selecting one of the pluralityof symbols of the connection identifier broadcast channel in the timeinterval to send the first connection identifier broadcast signal. 6.The method of claim 5, further comprising: receiving a broadcast signalfrom a common network timing source; and determining the value of a timecounter, wherein the value of the time counter is determined as afunction of the received broadcast signal and changes from one timeinterval to another, and the selected one of the plurality of symbols isselected as a function of the value of the time counter.
 7. The methodof claim 5, wherein each of the plurality of symbols is an OFDM symbolincluding a plurality of tones, and the first connection identifierbroadcast signal is sent in one of the plurality of tones in theselected one of plurality of symbols.
 8. The method of claim 7, whereinthe combination of selected OFDM symbol and tone is determined as afunction of the first connection identifier and wherein a differentconnection identifier corresponds to a different combination of selectedOFDM symbol and tone.
 9. The method of claim 7, wherein a plurality OFDMsymbols are associated with the first connection identifier, and whereinthe selected one of the plurality of symbols is selected from theplurality of OFDM symbols being associated with the first connectionidentifier as a function determined by both the first and the seconddevices.
 10. The method of claim 9, wherein the second connectionidentifier broadcast signal is received in the remaining OFDM symbols ofthe plurality of OFDM symbols being associated with the first connectionidentifier.
 11. The method of claim 2, further comprising: prior toswitching to the second connection identifier, monitoring a connectionidentifier broadcast channel corresponding to the second connectionidentifier to determine whether the second connection identifier isbeing utilized by other connections in the proximity; and determining toswitch to the second connection identifier if it is determined that thesecond connection identifier is not being utilized by another connectionin the proximity.
 12. The method of claim 11, wherein determiningwhether the second connection identifier is being utilized by otherconnections in the proximity further comprising: detecting the presenceof a connection identifier broadcast signal in the connection identifierbroadcast channel, the connection identifier broadcast signalcorresponding to the second connection identifier; and measuring thesignal strength of the connection identifier broadcast signal if thepresence of the connection identifier broadcast signal is detected. 13.The method of claim 1, wherein the connection identifier broadcastchannel is part of a frequency spectrum shared with a plurality of otherpeer-to-peer connections.
 14. A first device configured to utilize afirst connection identifier for a peer-to-peer communication connectionbetween the first device and a second device in a wirelesscommunications network, comprising: a transmitter and receiver forestablishing the wireless peer-to-peer communication connection; and aprocessing circuit adapted to perform peer to peer communicationsthrough the transmitter and receiver over a peer-to-peer communicationchannel, the processing circuit configured to: send a first connectionidentifier broadcast signal corresponding to the first connectionidentifier in a connection identifier broadcast channel; monitor theconnection identifier broadcast channel to determine whether the firstconnection identifier is being utilized by another connection in theproximity; and switch to a second connection identifier if it isdetermined that the first connection identifier is being utilized byanother connection in the proximity.
 15. The first device of claim 14,wherein the first and second connection identifiers belong to apredetermined set of a plurality of connection identifiers.
 16. Thefirst device of claim 14, wherein the connection identifier broadcastchannel includes a plurality of symbols in a time interval, the firstconnection identifier broadcast signal is sent in one of the symbols,and to monitor the connection identifier broadcast channel theprocessing circuit is further adapted to: receive a signal in theremaining symbols of the connection identifier broadcast channel in thetime interval; detect the presence of a second connection identifierbroadcast signal in the received signal, the second connectionidentifier broadcast signal corresponding to the first connectionidentifier; and measure the signal strength of the detected secondconnection identifier broadcast signal if the presence of the secondconnection identifier broadcast signal is detected.
 17. The first deviceof claim 16, wherein it is determined that the first connectionidentifier is being utilized by other connections in the proximity if itis determined that one of either: the second connection identifierbroadcast signal is present in the received signal, the signal strengthof the second connection identifier broadcast signal in the receivedsignal is above certain threshold, the ratio of the signal strength ofthe second connection identifier broadcast signal and the signalstrength of a connection identifier broadcast signal corresponding toanother connection identifier in the received signal is above certainthreshold.
 18. The first device of claim 16, wherein the processingcircuit is further adapted to: selecting one of the plurality of symbolsof the connection identifier broadcast channel in the time interval tosend the first connection identifier broadcast signal prior to sendingthe first connection identifier broadcast signal.
 19. The first deviceof claim 18, wherein the processing circuit is further adapted to:receive a broadcast signal from a common network timing source; anddetermine the value of a time counter, wherein the value of the timecounter is determined as a function of the received broadcast signal andchanges from one time interval to another, and the selected one of theplurality of symbols is selected as a function of the value of the timecounter.
 20. The first device of claim 18, wherein each of the pluralityof symbols is an OFDM symbol including a plurality of tones, and thefirst connection identifier broadcast signal is sent in one of theplurality of tones in the selected one of plurality of symbols.
 21. Thefirst device of claim 20, wherein the combination of selected OFDMsymbol and tone is determined as a function of the first connectionidentifier and wherein a different connection identifier corresponds toa different combination of selected OFDM symbol and tone.
 22. The firstdevice of claim 20, wherein a plurality of OFDM symbols are associatedwith the first connection identifier, and wherein the selected one ofthe plurality of symbols is selected from the plurality of OFDM symbolsbeing associated with the first connection identifier as a functiondetermined by both the first and the second devices.
 23. The firstdevice of claim 22, wherein the second connection identifier broadcastsignal is received in the remaining OFDM symbols of the plurality ofOFDM symbols being associated with the first connection identifier. 24.The first device of claim 14, wherein the processing circuit is furtheradapted to: prior to switching to the second connection identifier,monitor a connection identifier broadcast channel corresponding to thesecond connection identifier to determine whether the second connectionidentifier is being utilized by other connections in the proximity; anddetermine to switch to the second connection identifier if it isdetermined that the second connection identifier is not being utilizedby another connection in the proximity.
 25. The first device of claim24, wherein to determine whether the second connection identifier is notbeing utilized by other connections in the proximity, the processingcircuit is further adapted to: detect the presence of a connectionidentifier broadcast signal in the connection identifier broadcastchannel, the connection identifier broadcast signal corresponding to thesecond connection identifier; and measure the signal strength of theconnection identifier broadcast signal if the presence of the connectionidentifier broadcast signal is detected.
 26. A first device configuredto utilize a first connection identifier for a peer-to-peercommunication connection between the first device and a second device ina wireless communications network, comprising: means for sending a firstconnection identifier broadcast signal corresponding to the firstconnection identifier in a connection identifier broadcast channel;means for monitoring the connection identifier broadcast channel todetermine whether the first connection identifier is being utilized byanother connection in the proximity; and means for switching to a secondconnection identifier if it is determined that the first connectionidentifier is being utilized by another connection in the proximity. 27.The first device of claim 26, wherein the first and second connectionidentifiers belong to a predetermined set of a plurality of connectionidentifiers.
 28. The first device of claim 26, wherein the connectionidentifier broadcast channel includes a plurality of symbols in a timeinterval, the first connection identifier broadcast signal is sent inone of the symbols, and further comprising: means for receiving a signalin the remaining symbols of the connection identifier broadcast channelin the time interval; means for detecting the presence of a secondconnection identifier broadcast signal in the received signal, thesecond connection identifier broadcast signal corresponding to the firstconnection identifier; and means for measuring the signal strength ofthe detected second connection identifier broadcast signal if thepresence of the second connection identifier broadcast signal isdetected.
 29. The first device of claim 28, wherein it is determinedthat the first connection identifier is being utilized by otherconnections in the proximity if one of either: the second connectionidentifier broadcast signal is present in the received signal, thesignal strength of the second connection identifier broadcast signal inthe received signal is above certain threshold, or the ratio of thesignal strength of the second connection identifier broadcast signal andthe signal strength of a connection identifier broadcast signalcorresponding to another connection identifier in the received signal isabove second threshold.
 30. The first device of claim 28, furthercomprising: means for selecting one of the plurality of symbols of theconnection identifier broadcast channel in the time interval to send thefirst connection identifier broadcast signal.
 31. The first device ofclaim 30, further comprising: means for receiving a broadcast signalfrom a common network timing source; and means for determining the valueof a time counter, wherein the value of the time counter is determinedas a function of the received broadcast signal and changes from one timeinterval to another, and the selected one of the plurality of symbols isselected as a function of the value of the time counter.
 32. The firstdevice of claim 30, wherein each of the plurality of symbols is an OFDMsymbol including a plurality of tones, and the first connectionidentifier broadcast signal is sent in one of the plurality of tones inthe selected one of plurality of symbols.
 33. The first device of claim32, wherein the combination of selected OFDM symbol and tone isdetermined as a function of the first connection identifier and whereina different connection identifier corresponds to a different combinationof selected OFDM symbol and tone.
 34. The first device of claim 32,wherein a plurality of OFDM symbols are associated with the firstconnection identifier, and wherein the selected one of the plurality ofsymbols is selected from the plurality of OFDM symbols being associatedwith the first connection identifier as a function determined by boththe first and the second devices, and the second connection identifierbroadcast signal is received in the remaining OFDM symbols of theplurality of OFDM symbols being associated with the first connectionidentifier.
 35. A circuit for utilizing a first connection identifierfor a peer-to-peer communication connection between a first device and asecond device in a wireless communications network, wherein the circuitoperates in a first device and is adapted to: send a first connectionidentifier broadcast signal corresponding to the first connectionidentifier in a connection identifier broadcast channel; monitor theconnection identifier broadcast channel to determine whether the firstconnection identifier is being utilized by another connection in theproximity; and switch to a second connection identifier if it isdetermined that the first connection identifier is being utilized byanother connection in the proximity.
 36. The circuit of claim 35,wherein the connection identifier broadcast channel includes a pluralityof symbols in a time interval, the first connection identifier broadcastsignal is sent in one of the symbols, the circuit further adapted to:receive a signal in the remaining symbols of the connection identifierbroadcast channel in the time interval; detect the presence of a secondconnection identifier broadcast signal in the received signal, thesecond connection identifier broadcast signal corresponding to the firstconnection identifier; measure the signal strength of the detectedsecond connection identifier broadcast signal if the presence of thesecond connection identifier broadcast signal is detected; and selectone of the plurality of symbols of the connection identifier broadcastchannel in the time interval to send the first connection identifierbroadcast signal.
 37. The circuit of claim 36, wherein it is determinedthat the first connection identifier is being utilized by otherconnections in the proximity if one of either: the second connectionidentifier broadcast signal is present in the received signal, thesignal strength of the second connection identifier broadcast signal inthe received signal is above certain threshold, or the ratio of thesignal strength of the second connection identifier broadcast signal andthe signal strength of a connection identifier broadcast signalcorresponding to another connection identifier in the received signal isabove second threshold.
 38. A non-transitory machine-readable mediumcomprising instructions for a first device to utilize a first connectionidentifier for a peer-to-peer communication connection between the firstdevice and a second device in a wireless communications network, whichwhen executed by a processor causes the processor to: send a firstconnection identifier broadcast signal corresponding to the firstconnection identifier in a connection identifier broadcast channel;monitor the connection identifier broadcast channel to determine whetherthe first connection identifier is being utilized by another connectionin the proximity; and switch to a second connection identifier if it isdetermined that the first connection identifier is being utilized byanother connection in the proximity.
 39. The non-transitorymachine-readable medium of claim 38, wherein the connection identifierbroadcast channel includes a plurality of symbols in a time interval,the first connection identifier broadcast signal is sent in one of thesymbols, and wherein said non-transitory machine-readable medium furthercomprises instructions to: receive a signal in the remaining symbols ofthe connection identifier broadcast channel in the time interval; detectthe presence of a second connection identifier broadcast signal in thereceived signal, the second connection identifier broadcast signalcorresponding to the first connection identifier; and measure the signalstrength of the detected second connection identifier broadcast signalif the presence of the second connection identifier broadcast signal isdetected.
 40. The non-transitory machine-readable medium of claim 39,wherein it is determined that the first connection identifier is beingutilized by other connections in the proximity if one of either: thesecond connection identifier broadcast signal is present in the receivedsignal, the signal strength of the second connection identifierbroadcast signal in the received signal is above certain threshold, orthe ratio of the signal strength of the second connection identifierbroadcast signal and the signal strength of a connection identifierbroadcast signal corresponding to another connection identifier in thereceived signal is above second threshold.